The present invention relates generally to the field of dust removal from air, and, more particularly, to a new air filtration system for use in combination with an industrial sweeping and collection device for filtering dust from air pulled by high speed air flow through the collection device before exhausting the air therefrom.
Heretofore, industrial sweeper and scrubber machines existed for cleaning of large areas such as railroad tracks and pavement surfaces. In operation of such machines dirt and debris were collected by various means and mechanically or otherwise moved to a bin or hopper for temporary storage or transport. These machines traditionally had no provision whatsoever for dust control. Accordingly, the large quantities of airborne dust inherently created in such cleaning operations were an inconvenience and a health hazard for the operator of the machine, as well as other persons in the nearby vicinity of its operation.
With the advent of workers' compensation and clean air laws, as well as generally increased public health awareness, it has become desirable to include in industrial scrubbing and sweeping equipment some adaptation for eliminating fugitive dust raised in the sweeping operation, for the health of the operator of the equipment as well as to keep air pollution generally at a low level. One such adaptation was to use large quantities of water to dampen the surface being cleaned. This method proved to be messy and wasteful of both water and fuel. Water sprayed on the surface created mud that remained as the sweeper moved on, and increased fuel was necessary to transport the water.
Thus it was desired to develop a dust control system which did not make use of water and which was adaptable at least to some pre-existing sweeper machines. Previously, air filtration systems of various types have been known for use in particular industrial situations. Some industrial applications, including for example, certain railroad track and pavement sweepers, as well as some mining operations have used drum-type pleated paper filters with limited success.
These known filtration systems all have suffered from certain drawbacks which have made use thereof at least troublesome and inefficient. Of particular concern have been limitations on air flow rate through the filters and clogging of the filter media with fine particulate matter which is filtered from the system's exhaust air flow. Of course, as the porous membrane of a filter becomes blocked the flow of air therethrough becomes less and less efficient until the filter becomes essentially non-functional.
And, although previous attempts have been made at developing air filtration systems in which the filter media can be purged by backward flushing with bursts of air, to clear the media pores of blockage, these attempts have been unsatisfactory with regard to the thoroughness of the purging and the overall efficiency of the air filtration system, particularly in terms of volume of air filtered per unit time.
Accordingly, the new air filtration system addresses these past problems by provision of a particular arrangement of redesigned filter units mounted within a debris collection hopper having a unique wall arrangement therein which is particularly advantageous when used in combination with such redesigned filter units. Further, the new design of the barrel-type air filters and the particular arrangement thereof, along with a purge air diffuser adaptation, permits the filters to be much more thoroughly purged than previously possible. Consequently, the enhanced filter purging permits the new air filtration system as a whole to be much more effective in cleansing large volumes of air drawn through the sweeper unit.
Thus, it is an object of the present invention to provide an air filtration system for use in a sweeping device, which filtration system provides superior cleansing of a large volume of air at a high rate of speed on a constant basis while using a minimum amount of filtration substrate material.
It is further among the objects of the present invention, having the features enumerated, that means are provided for particularly proficient purging of the filters of the new system by selectively timed, strong bursts of air in a flow direction opposite to the normal filtration air flow direction.
It is also among the objects of the present invention, having the above-mentioned features, that the new air filtration system be structured in a such a manner as to enable improved economy of manufacture thereof.
Accordingly, in furtherance of the above objects, the present invention is, briefly, an air filtration system for use in capturing fugitive dust in industrial sweeping operations. The system includes a hopper having internal structure for causing change in the direction of flow of suction air which enters the hopper along with debris collected during an industrial sweeping operation. The system also has a plurality of filters disposed within the hopper for filtering the suction air. Each one of the plurality of filters has filter media therein which can be repeatedly purged for cleaning and continuous reuse thereof. And the system is adapted for providing repeated purging blasts of air to the plurality of filters. Also in the system is structure associated with each one of the plurality of filters for causing the purging blasts of air to clean substantially the entire filter media of each one of the filters, and structure for creating suction air which is pulled through the hopper and the filters disposed therein before exit of the suction air from the hopper substantially free from debris, particulate matter and fugitive dust which is collected by the system.
The invention is also, briefly, the system described wherein the hopper is enclosed and has a right side wall and a left side wall, with respect to the position of an operator of the system, a front wall and a rear wall, a floor and a roof, and wherein the internal structure in the hopper for causing change in direction of the suction air includes an arrangement of walls disposed within the hopper in transverse relationship to the longitudinal axis thereof.
The invention is further, briefly, the system described, wherein the arrangement of walls includes a first wall, a second wall and a third wall disposed in relationship to each other so as to cause the suction air flow to change in direction to such a degree as to, in combination with the effect of gravity, cause large pieces of debris and relatively smaller particulate matter to be removed from the flow of suction air prior to contacting the plurality of filters disposed within the hopper.
Moreover, the invention is, briefly, for use in an industrial sweeping apparatus for capturing fugitive dust created by the sweeping process, wherein the sweeping apparatus has debris collection structure for transfer of debris from a sweeping portion to a hopper portion, and an air filtration system which includes structure for creating suction air flow, structure for changing the direction of suction air flow, to thereby enhance removal of large debris and particulate matter from the suction air, filters for removal of dust and fine particulate matter from the suction air flow, structure for automatically purging the entire filters of dust and fine particulate matter removed from the suction air flow, and structure for removing the filtered suction air from the system.
Further objects will be in part apparent and in part pointed out hereinbelow.